Color me confused, I read your post twice, and I am still confused.
You are thinking about buying a Nacra because someone else told you the Hobie you have is heavy ?
What is it that you percieve you Gain by making the swap ?
What is it you lose by keeping the Hobie ?
I've sailed both, they are both nice boats, parts for the Hobie are much easier to find. A class to race in is much easier to find. It is a no brainer to me, but hey, I don't walk in your shoes.

Stephen
H-18